Timeswitch question

[Mike Tomlinson]

Just opened a Suretime mechanical timeswitch made by Timeguard Ltd. It's one of those with a dial where you push in little fingers to indicate the on-times you want.

The leaflet inside says "This timeswitch can be used to control domestic appliances such as fans and heaters rated up to 13A (3kW), also washing machines and dishwashers"

Having seem the flimsy interior wiring of typical timeswitches, I very much doubt I'd put a heavy load like a washing machine on one.

But what gets me is "this timeswitch is NOT suitable for use with fluorescent lighting (low energy compact and linear tube types) and discharge lamps."

which is, of course, exactly what I want it for. Why should this be?

[Andrew Gabriel]

Seems like duff instructions to me. What's the model number? I hope the instructions give additional warning about using timeswitches to control heaters - it's all too easy to put something in front of a heater which is off, and use of a timeswitch means it might come on later where no one's around to see it burst into flames.

Washing machine isn't a heavy load - the heater is only used for a short time. (Large tumble drier could be different though.)

[Harry Bloomfield]

Mike Tomlinson formulated on Sunday :

Both are highly inductive loads, where as a washing machine is mostly (aside from the motor) a resistive load. The washer's motor will not be switched on by the time clock, but by the washers own timer a little later once it has filled up. It is not just the running current which needs to be considered, but the inductive load switching when rating contacts. Time clocks also switch quite slowly, increasing the arc time.

[Mike Tomlinson]

In article , Harry Bloomfield writes

Yes, I would have said the major part of the load would be the heater element, which is resistive.

Good point. Hadn't thought of that.

[Mike Tomlinson]

In article , Andrew Gabriel writes

Sorry, should have thought to menti Operating temp 5C to 55C Operating voltage 220-240V AC 50Hz Contact rating 13A resistive, 4A inductive, 300W filament lighting

4A inductive doesn't look like a problem for a single energy-saver lamp to me. I'd be worried if it took 4A!

Nope, not a mention.

[Les Desser]

In article , Mike Tomlinson Sun, 9 May 2010 19:49:09 writes

That is only 1.3A! Why so low?

[Mike Tomlinson]

In article , Les Desser writes

Don't know. Wonder if it's a misprint and they meant 3000W?

I'm using it with an 11W energy saver and it seems ok.

[NT]

CFLs are mostly rectifier resevoir inputs, you can happily run them on mechanical timeswitches, but need to stick to well below 3kW, but I dont see that being a problem in any normal domestic lighting app.

FWIW fitting a snubber across the timer's switch would increase the loads it could handle and its life expectancy.

NT

[pete]

I think the life expectancy of these cheapo timers is determined more by the plastic used in the mechaniscs than the quality of the microswitch. Occasionally I forget and buy one of these. The last one being from a branch of well-known high street electronics stores. It lasted about two months before the dial stopped rotating whenever it hit a "set" finger and the trigger thingy inside became so worn that it wasn't pushed closed when the finger went past. After that I remember why I don't buy them any more and go for the electronic timers instead.

[Mike Tomlinson]

In article , pete writes

I used to buy electronic timers, but they all ran too hot for me to be entirely comfortable with and suffered from bad caps (failure of the electrolytic capacitors).